package scalar

import "gonum.org/v1/gonum/floats/scalar"

Package scalar provides a set of helper routines for dealing with float64 values.

Index ¶

• func EqualWithinAbs(a, b, tol float64) bool
• func EqualWithinAbsOrRel(a, b, absTol, relTol float64) bool
• func EqualWithinRel(a, b, tol float64) bool
• func EqualWithinULP(a, b float64, ulp uint) bool
• func NaNPayload(f float64) (payload uint64, ok bool)
• func NaNWith(payload uint64) float64
• func ParseWithNA(s, missing string) (value, weight float64, err error)
• func Round(x float64, prec int) float64
• func RoundEven(x float64, prec int) float64
• func Same(a, b float64) bool

Examples ¶

• ParseWithNA

Functions ¶

func EqualWithinAbs ¶

func EqualWithinAbs(a, b, tol float64) bool

EqualWithinAbs returns true when a and b have an absolute difference not greater than tol.

func EqualWithinAbsOrRel ¶

func EqualWithinAbsOrRel(a, b, absTol, relTol float64) bool

EqualWithinAbsOrRel returns true when a and b are equal to within the absolute or relative tolerances. See EqualWithinAbs and EqualWithinRel for details.

func EqualWithinRel ¶

func EqualWithinRel(a, b, tol float64) bool

EqualWithinRel returns true when the difference between a and b is not greater than tol times the greater absolute value of a and b,

abs(a-b) <= tol * max(abs(a), abs(b)).

func EqualWithinULP ¶

func EqualWithinULP(a, b float64, ulp uint) bool

EqualWithinULP returns true when a and b are equal to within the specified number of floating point units in the last place.

func NaNPayload ¶

func NaNPayload(f float64) (payload uint64, ok bool)

NaNPayload returns the lowest 51 bits payload of an IEEE 754 "quiet not-a-number". For values of f other than quiet-NaN, NaNPayload returns zero and false.

func NaNWith ¶

func NaNWith(payload uint64) float64

NaNWith returns an IEEE 754 "quiet not-a-number" value with the payload specified in the low 51 bits of payload. The NaN returned by math.NaN has a bit pattern equal to NaNWith(1).

func ParseWithNA ¶

func ParseWithNA(s, missing string) (value, weight float64, err error)

ParseWithNA converts the string s to a float64 in value. If s equals missing, weight is returned as 0, otherwise 1.

package main

import (
	"bufio"
	"fmt"
	"log"
	"strings"

	"gonum.org/v1/gonum/floats/scalar"
	"gonum.org/v1/gonum/stat"
)

func main() {
	// Calculate the mean of a list of numbers
	// ignoring missing values.
	const data = `6
missing
4
`

	var vals, weights []float64
	sc := bufio.NewScanner(strings.NewReader(data))
	for sc.Scan() {
		v, w, err := scalar.ParseWithNA(sc.Text(), "missing")
		if err != nil {
			log.Fatal(err)
		}
		vals = append(vals, v)
		weights = append(weights, w)
	}
	err := sc.Err()
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(stat.Mean(vals, weights))

}

5

func Round ¶

func Round(x float64, prec int) float64

Round returns the half away from zero rounded value of x with prec precision.

Special cases are:

Round(±0) = +0
Round(±Inf) = ±Inf
Round(NaN) = NaN

func RoundEven ¶

func RoundEven(x float64, prec int) float64

RoundEven returns the half even rounded value of x with prec precision.

Special cases are:

RoundEven(±0) = +0
RoundEven(±Inf) = ±Inf
RoundEven(NaN) = NaN

func Same ¶

func Same(a, b float64) bool

Same returns true when the inputs have the same value, allowing NaN equality.

Source Files ¶

doc.go scalar.go